The present invention relates to heating devices to be installed in fluid control apparatus comprising a massflow controller, on-off valves, etc., for example, for preventing condensation and for preventing the re-liquefaction of a gas as converted from a fluid which is in the form of a liquid at room temperature.
For use in fluid control apparatus which comprise a massflow controller, on-off valves, pressure reducing valves, pressure sensors, etc. in combination, heating devices are known which include those comprising rod heaters and those comprising tape heaters.
In the case where the lateral side of the fluid control apparatus has many projections or indentations when seen from above, it is difficult to install a tape heater along the lateral side of the apparatus, so that rod heaters 44 are used, for example, as shown in FIG. 4. Vertical rod heaters 44 are suitably arranged between a massflow controller 41 and an on-off valve 42, and between the valve 42 and another on-off valve 43. The controller 41 is mounted on a panel 45 and removable upward, and the rod heaters 44 are so arranged as not to interfere with the controller 41 when the controller is removed upward.
The conventional heating device of the rod heater type for use in fluid control apparatus has the problem of producing a difference in heating effect between the portion in contact with the rod heater and the portion out of contact therewith.